High-frequency vacuum tube oscillator



June 20, 1944. CHEVlGNY 2,351,744

HIGH FREQUENCY VACUUM TUBE OSCILLATOR Filed Dec. 24, 1942 8 24 32 48 r% i v J6 14 50 E x 6g *6) INVENTOR IIUL s. CHEWG/YY ATTORNEY Patented June 20, 1944 g UNITED STATES PATENT OFFICE.

' HIGH-FREQUENCY VACUUM TUB oscnm'roa Application December 24, 1942, Serial No. 470,061

Claims.

This invention relates to improvements in high frequency vacuum tube oscillators, and more particularly to a tube in which the oscillating circuit is formed as a part of the vacuum tube structure.

A broad object of the invention is the provision of a novel unitary vacuum tube oscillator structure.

Another object of this invention'is to provide a unitary vacuum tube oscillator structure in which the anode and grid are coupled by means of concentric spheres forming a resonant chamber between them.

A further object of this invention is the provision of a novel unitary vacuum tube oscillator structure having a concentric annular cathode, grid and anode elements, in which the grid and anode are coupled by a resonant chamber formed of concentric spheres, and the grid and cathode are coupled through a coaxial line.

A subsidiary object of this invention is the provision of a novel annular cathode structure.

These and other objects and advantages of the present invention will become apparent from the following description of a preferred embodiment chamber II with an inner spherical metal shell I2. The outer spherical shell I0 is open at one side, this open side being formed with an internal ridge l4 whose internal annular face is adapted to act as an annular anode. An anode ring l6 surrounds and is inserted in the outer notch formed by the internal ridge l4, and may serve as an anode cooling means, and as a high voltage supply connector.

The inner spherical shell i2 is also open at one end, the open end of the shell being preferably turned in to form a circular flange l8 supported upon a circular metal disk 20. Between the flange I8 and the disk 20 are provided an inverted cup-shaped member 22 adapted to serve as a grid support and a further metal ring 24 which acts to support the cylindrical sides of the cupshaped member 22. Means such as screws 26 passing through the flange l8 and the bases of the members 22 and 24 serve to rigidly secure these parts together and to the metal disk 20. The open side of the cup-shaped member 22 is preferably formed with an outwardly slanting lip 28 for supporting the annular grid 30 either directly or through an intermediate ring 32. The metal disk 20, the cup-shaped member' 22, and the annular grid 30 are positioned coaxially with one another with their axes intersecting the center of the concentric spheres so that the grid 30 will be spaced closely to and concentric with the annular anode i4.

The lower side of the metal disk 20 is preferably formed with an inserted threaded bushing 84 into which is screwed a flanged bushing 36. The flange 38 of the bushing 36 is pressed on one side against the threaded bushing 34 and the metal disk 20 and, on the other side, is connected to a flange 40 of a metal tube 42 through an insulating layer 44. The tube 42 thus forms a grid line connected to the annular'grid through a condenser 46 whose plates comprise the flanges 38 and 4D and whose dielectric is formed by the insulation 44. It is proposed in accordance with the present invention that the parts 36, 38, 40, 42 and 44 be formed a an integral replaceable unit which may be threaded into the bushing 34. A number of such units may be tried for each oscillator, each unit being provided with a slightly different value for the capacitor 46, so that the optimum value for such capacitor can be used with each oscillator, as desired. Since a the metal disk 20 will preferably be made of copper, a soft metal whose threads would readily become distorted and worn, the threaded bushing 34 of a harder material such as nickel is used to threadably receive the replaceable grid condenser and line.

The lower side of the metal disk 20 is also provided with a thin annular depending knife-edge 48 which, through an annular glass seal 50 is connected to a metal ring. The latter, in turn. is connected by an annular U-shaped glass seal 54 to the annular knife-edge 56 depending from the anode 44. It will thus be seen that the annular knife-edge 56, the glass seal 54, the ring 52, the glass seal 50 and the metal disk 20 effectively seal off the lower side of the oscillator.

Mounted upon the metal ring 52 and surrounding the glass seal 50 is a cup-shaped member 58 provided with an outwardly slanting lip 59 which supports about it periphery a plurality of depending wires 60, spaced from one another about the circumference of the lip to form an annular cathode mounted within and concentricwith the annulargrid 30. This construction, illustrated in more detail in Fig. 2, permits a ready alignment of the cathode elements 80 which, in the preferred form of invention, are made of thoriated tungsten wire in the shape of an inverted V, while the supporting cup-shaped member is made of tantalum. The base 62 of the cup-shaped member 58 rests upon the ring 52 and may be attached thereto by suitable means such as screws 64.

The inner periphery oi the ring 52 is preferably iormed threaded and supports the threaded end of a metal cylinder 66 surrounding the metal tube 42 and forming with it a coaxial line ti. The coaxial line 61 may be tuned by a slidable ring t8 mounted between and contacting the metal tube i2 and the cylinder I56. Adjustment of the slidable ring 68 may be efiected in any manner well known to the art. Bias voltage may be applied to the grid through a suitable lead 69 passing within the tub t2 and connected to the metal disk 20. It will be clear to those skilled in this art that by reason of the construction just described, the cathode 60 and the grid 30 are coupled first through the condenser 36 and then through the coaxial line 67.

Within the space between the depending cathode wires 60 and the lip of the cathode supporting member 58 is positioned the cathode-energizing filament 10 which, in the preferred form of invention, may be of the cathode-bombardment type. It will be noted, particularly from a study of Fig. 2, that the filament 10 may be positioned closely to the depending portion of the cathode 60 which, of course, in the construction shown, is the active cathode portion while at the same time the filament i is relatively widely spaced from the top of the cathode and from the lip of the supporting member 58. Thus the desired portion of the cathode is more highly energized than the supporting structure or the unused portions of the cathode, resulting in a more eflicient utilization of power. Moreover, the bent-over section of the cathode wires 50 and the supporting member 58 are not subjected to as high a heat and will not distort so as to move the cathode wires out of proper alinement. The spacing between the cathode wires 'tflwhile maintained extremely small, still is sufficient to permit the escape of excess heat. The filament i0 may be held in plates through a plurality of generally vertical rods of which there may be two rods, such as the rod 12, supported by and passing through the base of the glass seal 54 to form the filament leads, and also one or more circumferentially spaced rods '54, supported by the base of the glass seal 54 but not extending therethrough, serving as intermediate filament supports.

The upper side of the outer spherical shell l0 may be provided with another opening it and, in such case, a portion of the shell surface may be bent outwardly to form an annular ring 18 strengthened by a relatively thick surrounding ring 80 to which is threaded a hollow metal cylinder 82 forming one of the output leads from the oscillator. The cylinder 82 surrounds and is coaxial with a hollow rod 84 which, with the cylinder 82 forms a coaxial output line 85. The rod 84 may be supported relatively to the metal cylinder 82 through a cup-shaped glass seal 86 surrounding and engaging the up-turned ends of the ring 18 from the outer shell m. The end to 88 of the internal metal rod 84 projects into the space between the spherical shells l0 and I2 forming the resonant chamber H, so that this output lead is inductively coupled with the resonant chamber H, while the cylinder 82 is directly connected to the shell it.

The equivalent circuit of the vacuum tube oscillator illustrated in Fig. 1 may be more clearly perceived from the circuit diagram in Fig. 3 from which it will be noted that the coaxial line 67 connected between the grid and cathode may form the oscillator input, noting furthermore that the connection to the grid will be through the condenser 68. Grid bias will be supplied through the lead 69 and filament voltage through the leads 12. The grid and anode will be coupled through the resonant chamber H, as indicated, while the output is taken from the coaxial line connected, on the one hand, to the shell I0 of the resonant chamber and, on the other hand, inductively linked with the resonant chamber itself.

One feature of the present invention which is advantageous as compared with other high frequency oscillators. is the fact that by the use of spherical shells forming the resonator, the inter-shell capacitances are substantially equal and constant throughout the entire resonator. Applicants take advantage of this desirable arrangement through a simple constructional mounting of the parts forming the vacuum tube, including a novel formation of the anode as an integral part of the outer shell ID, a novel cathode construction, and a novel coaxial input line which may be not only tuned but which may be easily replaced to provide series grid capacitors of desired values.

It will thus be seen that I have provided a vacuum tube oscillator which fulfills the objects primarily stated, and while I have described the principles of my invention in connection with specific apparatus involving specific details of construction, it is to be clearly understood that the description of such details has been made only by way of example and not as a limitation on the scope of my invention, as set forth in the objects and the accompanying claims.

I claim:

1. A high frequency vacuum tube oscillator including, in combination, a pair of concentric spherical metal shells open at one side and forming a resonant chamber between them, the outer shell being formed with an internal annular ridge having a fiat internal peripheral surface about its open side, constituting an annular anode, an annular grid spaced within and concentric with said annular anode, means supporting said grid from the open side of the inner spherical shell, whereby said grid and anode are coupled through the resonant chamber formed by said shells, an annular cathode spaced within and concentric with said annular grid, and means sealing the open side of each metal shell, said last means including further means supporting said cathode.

2. A high frequency vacuum tube oscillator including, in combination, a pair of concentric spherical metal shells open at one side and forming a resonant chamber between them, the outer shell being formed with an internal annular ridge having a flat internal peripheral surface about its open side, constituting an annular anode, an annular grid spaced within and concentric with said annular anode, means supporting said grid from the open side of the inner spherical shell.

whereby said grid and anode are coupled through the resonant chamber formed by said shells, an annular cathode spaced within and concentric with said annular grid, a hollow cylindrical metal tube whose axis intersects the center of said spherical shells, connected to said grid-supporting means and extending outwardly through the open sides of said spherical shells, a metal ring supporting said cathode, a second hollow cylindrical metal tube coaxial with and surrounding the first cylindrical tube, supported from said metal ring and forming a coaxial line with said first cylindrical tube, and means sealing the open side of each metal shell, including means supporting said ring.

3. The combination according to claim 2, in combination with a slidable ring whose inner periphery contacts the first cylindrical tube and whose outer surface contacts the outer cylindrical tube for varying the length of said coaxial line.

4. The combination according to claim 2, in which the inner surface of said metal ring is threaded and the outer surface of the cylindrical tube is threaded and threadably engages the inner surface of the metal ring.

51 A high frequency vacuum tube oscillator including, in combination, a pair of concentric spherical metal shells open at one side and forming a resonant chamber between them, the outer shell being formed with an internal annular ridge having a flat internal peripheral surface about its open side, constituting an annular anode, an inverted cup-shaped member constituting a grid support, a metal disk, means clamping the open side of the inner metal shell to said disk with the base of said inverted cup-shaped member in-between, an annular grid supported from the periphery of said inverted cup-shaped member, within and concentric with the annular anode, a flanged bushing inserted in said metal disk, with one flange face lying against said disk, a thin layer of insulation on the other flange face, a metal cylinder having a flanged end lying against said insulation, a metal ring, sealing means supporting said metal ring between said through said opening into the resonant chamber between said shells.

7. A high frequency vacuum tube oscillator including, in combination, a pair of concentric spherical metal shells open at one side and forming a resonant chamber between them, an annular anode having an internal peripheral face formed about the open side of the outer shell, an annular grid spaced within and concentric with said annular anode, means supporting said grid from the open side of the inner spherical shell, whereby said grid and anode are coupled through the resonant chamber formed by said shells, an annular cathode spaced within and concentric with said annular grid, said cathode comprising a cup-shaped member with an outwardly slanting lip and a plurality of short wires each in the form of an inverted V, circumferentially spaced about said lip, one leg of the V being attached to the lip and the other leg depending therefrom substantially parallel to the surface of the surrounding grid, and means sealing the open side of each metal shell, said last means including further means supporting said cup-shaped memher.

8. The combination according to claim 7, in combination, with means positioned between the spaced depending legs of the cathode and the outer surface of said lip for energizing said depending legs, said means being positioned closely to said depending legs than to said lip.

9. The combination according to claim 7, in which said internal anode is formed as an 'integral continuation of said outer shell.

10. The combination according to claim 7, in which said grid-supporting means comprises an inverted cup-shaped member, means supporting said grid from the periphery of said inverted cup-shaped member, a metal disk, and means clamping the open side of the inner metal shell to said disk with the base of said-inverted cup V shaped member in between.

11. The combination accordingto claim 7, in which said grid-supporting mean comprises an inverted cup-shaped member, means supporting said grid from the periphery of said inverted cup-shaped member, a metal disk, and means clamping the open side of the inner metalshell to said disk with the base of said inverted cupshaped member in between, in combina'tion with a flanged bushing inserted in said metal-disk, with one flange face lying against said disk, a thin layer of insulation on the other flange face, a metal cylinder having a flanged end lying against said insulation, and a second hollow metal cylinder connected to said further supporting means, positioned about and coaxial with the first metal cylinder.

12. The combination according to claim 71, in

which said grid-supporting means comprises an inverted cup-shaped member, means supporting said grid from the periphery of said inverted cupshaped member, a metal disk, and means clamping the open side of the inner metal shell to said disk with the base of said inverted cup-shaped member in between, in combination with a flanged bushing inserted in said metal disk, with one flange face lying against said disk, a thin layer of insulation on the other flange face, a metal cylinder having a flanged end lying against said insulation, a second hollow metal cylinder connected to said further supporting means, po-

sitioned about and coaxial with the first metal cylinder, and adjustable short-circuiting means between said two metal cylinders.

13. A high frequency vacuum tube oscillator including, in combination, a pair of concentric spherical metal shells open at one side and forming a resonant chamber between them, an annular anode having an internal peripheral face formed about the open side of the outer shell, an annular grid spaced within and concentric with said annular anode, means supporting said grid from the open side of the inner spherical shell, whereby said grid and anode are coupled through the resonant chamber formed by said shells, an annular cathode spaced within and concentric with said annular grid, said cathode comprising a cup-shaped member with an outwardly slanting lip and a plurality of short wires in the form of an inverted V circumferentially spaced about said lip, one leg of the V being attached to the lip of the other leg depending thereirom substantially parallel to the surface of the surrounding grid, means sealing the open side of said metal shells, said means including further means supporting said cup-shaped member, the outer spherical shell being provided with an opening on the other side, a hollow metal cylinder having one end connected about said opening, and a metal cylindrical member mounted within and coaxial with said metal cylinder, projecting through said opening into the resonant chamber between said shells.

14. An annular cathode comprising, in combination, a cylindrical metal member having an outwardly slanting lip, and a plurality of short wires in th form of an inverted V, circumferentially spaced about said lip, one leg of the V being attached to the lip and the other leg depending therefrom substantially parallel to the longitudinal axis of the cylindrical member.

' 15. The combination according to claim. 14, in combination with cathode-energizing means mounted between said depending legs and the outer surface of said lip. 16. A high frequency vacuum tube oscillator including, in combination, a pair of concentric spherical metal shells open at one side and forming a resonant chamber between them, an annular anode having an internal peripheral face formed about the open side of the outer shell, an annular grid spaced within and concentric with said annular anode, means supporting said grid from the open side of the inner spherical shell, whereby said grid and anode are coupled through the resonant chamber formed by said shells, an annular cathode spaced within and concentric with said annular grid, said cathode comprising a cup-shaped member with an outwardly slanting lip and a plurality of short wires in the form of an inverted V, circumferentially spaced about said lip, one leg of the V being attached to the lip and the other leg depending therefrom substantially parallel to the surface of the surrounding grid, a hollow cylindrical metal tube whose axi intersects the center of said spherical shells, connected to said grid-supporting means and extending outwardly through the open sides of said spherical shells, a metal ring supporting said cup-shaped member, a second hollow cylindrical metal tube coaxial with and surrounding the first cylindrical tube, supported from said metal ring and forming a coaxial line with the first cylindrical tube, and means sealing the open sides of said metal shells, including means supporting said ring.

17. The combination according to claim 16, in which the inner surface of said metal ring is threaded and the outer surface of the second cylindrical tube is threaded and threadably engages the inner surface of the metal ring.

, c PAUL GEORGES CHEVIGNY. 

